Yes, I've seen it many times on my own beardies. It's just uneven shed, very common especially on adult dragons. A
bath every other day will help, but no need to worry or take special measures, it will come off. If his enclosure is very dry, a quick spritz with a spray bottle will help , too. Not a lot of water, just pull the trigger 2-3 times for a fine mist on the dragon without getting it too wet.